Efficient python programming...

[Roman Suzi]

On Fri, 7 Jun 2002, Peter Hansen wrote:

>Roman Suzi wrote:
>> 
>> On Fri, 7 Jun 2002, Peter Hansen wrote:
>> > You forgot the even more important first thing for a beginner:
>> > get it correct!  The only good way to do this is to write unit
>> > tests that prove it.  If you don't have tests, you don't have
>> > working code (or how can you prove it?).
>> 
>> To prove that code is correct is very difficult (practically impossible).
>> Unittests are there to prove that you have errors, not the other way
>> around.
>> 
>> Of course, they can increase your confidence in that optimized code is
>> equivalent to what you had before.
>
>I disagree, if the tests are written first (and run, proving that
>they will fail when the code is wrong or missing).
>
>The tests are executable requirement specifications.  Running
>them "proves" (yes, not 100%... nothing could) that the code
>meets the specs.  The specs could be wrong of course, but that
>doesn't mean the code is broken...

I can agree that tests give practical confidence in the 
tested code, but I was speaking about rigourous 
verification that code is 'correct'.

And tests can test only some subset of input-output
mapping. Making tests is an art, is not formal act.

I had no intention to say tests are useless, only that
they are not a method of proving the correctness of code
or correctenss of code modifications.


Sincerely yours, Roman Suzi
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